Development of a data acquisition system for electrical conductivity images of biological tissues via contactless measurements

The data acquisition system of a new medical imaging system is developed and system performance is presented. The ultimate aim of the system is to image electrical conductivity of biological tissues via contactless measurements. Two different measurement systems are designed based upon measurement of impedance change of an eddy current type sensor. The first design (based upon excitation of a single coil probe) gives 100 Hz output frequency change for a conductivity change of 1.9 mS/cm and is tested at high frequency (1.4 MHz). Second design (based on one excitation and one receiving coil) operates at low frequency (15 KHz) and gives 18 μV change in output voltage for similar conductivity variation. Field images of 30 mm diameter cylindrical objects were obtained while scanning a region of 225 cm². The sensitivities of the two systems show a possible wide scale use of these systems for measurement, monitoring and imaging of local conductivity variations in biological tissues.